During the next year we will initiate experiments using the new antibodies which we have prepared to attempt to determine the direction of growth (the addition of subunits to tail tubes to determine whether a built-in polarity exists). The idea is that we may be able to compare the tail tube-baseplates, which appear to be filled with something, with artificially emptied tubes which we know to be hollow. These will be compared by examining oriented gels of pellets of purified tail tubes by low angle x-ray diffraction in our laboratory. These experiments will be repeated ussng bacteriophage SPO1 to confirm the results obtained with bacteriophage T4.